Electrically operated mechanism



June 22, 1954 E. J. SCHULENBURG 2,682,004

ELECTRICALLY OPERATED MECHANISM Filed June 1, 1951 2 Sheets-Sheet 1 J5 INVENTOR.

June 22, 1954 E. J. SCHULENBURG 2,682,004

ELECTRICALLY OPERATED MECHANISM Filed June 1, 1951 2 Sheets-Sheet 2 j I F- by W IN V EN TOR.

Patented June 22, 1954 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to an electrically operated mechanism for advancing a device in steps.

The principal object of this invention is to provide an improved mechanism of this type which is simple in construction, inexpensive to manufacture and foolproof in operation, which utilizes gravity in its operation thereby avoiding the use of springs and the like heretofore conventionally used, and which needs substantially no servicing in use. While the mechanism of this invention is of general utility it is particularly adaptable for use in operating electric switching devices of traffic control systems, such as disclosed in my copending application, Ser. No. 229,413, filed June 1, 1951, such systems operating continuously over extended periods of time and under all types of adverse weather conditions with a minimum of care.

In carrying out this object of the invention, the electrically operated mechanism for rotatably advancing a device in steps may include a toothed ratchet wheel rotatably mounted on a horizontal axis for rotating the device. A solenoid is located above the ratchet wheel and has a vertical armature opening which may be offset from the horizontal axis of the ratchet Wheel. An armature of less width than the armature opening is freely movable in the armature opening and may engage at its lower end with the teeth of the toothed ratchet wheel. The armature is lifted upon energization of the solenoid and drops by gravity upon deenergization of the solenoid to engage a ratchet wheel tooth for rtatably advancing the ratchet wheel. The side of the armature opening nearest to the ratchet wheel is so located with respect to the ratchet wheel that, when the armature is lifted and engages that side of the armature opening, the lower end of the armature overlies the ratchet wheel tooth to be engaged by the subsequent dropping of the armature. Means are also provided for moving the armature into engagement with the side of the armature opening nearest to the ratchet wheel when the armature is lifted by the solenoid so that when the armature drops by gravity upon deenergization of the solenoid, the lower end of the armature necessarily engages the appropriate ratchet wheel tooth for advancing the ratchet wheel the proper distance.

This last mentioned means may include a guide means for the armature for maintaining the spacing between the armature and the side of the armature opening nearest to the ratchet 7 wheel less than the spacing between the armature and the side of the armature opening farthest from the ratchet wheel. As a result, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the side of the armature opening nearest to the ratchet wheel. This last mentioned means may also include a bevelled surface on the upper end of the armature, the bevelled surface facing the side of the armature nearest the ratchet wheel. This bevelled surface cooperates with the flux produced by the solenoid for attracting the upper end of the armature toward the side of the armature opening nearest the ratchet wheel. This bevelled surface also engages the upper end of the armatureopening to move the armature into engagement with the side of the armature opening nearest the ratchet wheel when the armature is lifted by the solenoid. The armature may also be provided with a slot on its side farthest from the ratchet wheel for further assisting movement of the armature toward the side of the armature opening nearest the ratchet wheel. Thus, means are provided upon energization of the solenoid for positively moving the armature over the appropriate ratchet wheel tooth so that when the solenoid is deenergized, the proper ratchet wheel tooth is engaged by the dropping armature for advancing the ratchet Wheel the distance of one tooth and all of this is accomplished without the use of springs and the like, which have heretofore been conventionally used.

Further objects of this invention reside in the details of construction of the electrically operated mechanism and in the cooperative relationship between the component parts thereof.

Other objects and advantages of this invention will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawing, in which:

Fig. 1 is an elevational view partly in section of the electrically operated mechanism of this invention showing the solenoid deenergized;

Fig. 2 is an elevational View looking from the right of Fig. 1;

Figs. 3 and 4 are elevational views similar to Fig. 1 but showing the solenoid energized and illustrating different positions which the armature may assume; I

Figs. 5 and 6 are vertical sectional views similar to Figs. 1 and 3, illustrating a further form of the electrically operated mechanism of this in vention;

Fig. 7 is a side elevational view of the electrically operated mechanism illustrated in Figs. 5 and 6; and

clude a plurality of cams i2 mounted on a shaft 13 for performing control operations, such as operating switches in sequence, etc.

The electrically operated mechanism I includes a toothed ratchet wheel l5 which may be carried by the shaft is and which is rotatable about a horizontal axis. Rotation of the ratchet wheel I5 rotates the device I l. The ratchet wheel is is provided with a plurality of teeth I6 and the ratchet wheel is rotated in a clockwise direction, as illustrated in Fig. l. A pawl 11 pivoted on a suitable pin teeth IE to prevent counterclockwise rotation of the ratchet wheel IS.

A solenoid. is mounted above the ratchet wheel I5 and it includes a suitable electrical winding 20 and an O-shaped laminated core 2! forming a magnetic path. The solenoid is provided with a vertically arranged armature opening 22 which is offset from the horizontal axis of the ratchet wheel 15. This armature opening has an upper end 23, a side 24 nearest to the ratchetwheel l5 and a side 25 farthest from the ratchet wheel 15. The armature opening 2?. extends. through the bottom of the (J-shaped core 2|. The solenoid may be suitably mounted in position by means of brackets 23 carried by the core2l.

An armature 28 is freely movable in the armature opening 22 and the width of the armature 28 is less than the width of the armatur opening 22. The lower end 25 of the armature 2B is engageable with the teeth it of the ratchet wheel I5. Upon energization of the solenoid winding 20, the armature 28 is lifted and when the solenoid windin 2% is deenergized the armature 28 drops by gravity and the lower end 29 of the armature 23 engages the ratchet wheel teeth I8 for rotatably advancing the ratchet wheel IS the distance of one tooth. The side 24 of the arma ture opening 22 nearest to the ratchet Wheel is so located with respect to the ratchet wheel that when the armature 28 is lifted and engages that side of the armature opening, the lower end 29 of the armature overlies the ratchet wheel tooth is which is to he engaged by the subsequent droppin of the armature. ship is illustrated in Figs. 3 and 4 and the particular ratchet wheel tooth to be engaged by the armature when it drops is designated. at A in these figures.

The armature 23 provided with a pair of shoulders 36 for engagin the bifurcated ends 32 of a stationary guide means 3! when the armature drops by gravity. These shoulders 30, cooperating with the bifurcated ends 3.2 of the guide means 3 i, form. stop means for limiting the dropping movement of the armature and, hence, limits the advance of: the ratchet wheel IE to a distance of onetooth. The guide means 3! is also provided with a guide surface 33 adapted to be engaged by the side of the armature t8 opposite.

the ratchet wheel is. This guide surface 33 of the guide means 31 operates to maintain the spacing between the armature 28 and the side 24 of it engages the ratchet.

This overlying relation-' the armature opening nearest to the ratchet Wheel less than the spacing between the armature 28 and the side of the armature opening farthest from the ratchet wheel. Thus, when the solenoid winding 20 is energized to lift the armature 28, the armature is magnetically attracted into engagement with the side 24 of the armature opening nearest to the ratchet wheel l5, as is illustrated in Fig. 3. In this. way the lower end 29 of the armature 28 overlies. the particular tooth A of the ratchet wheel l5 which is to be engaged by the armature 28 when it subsequently drops by gravity. The upper end of the'2lrlll&t111e 23 is bevelled as at 35 and the bevelled surface faces toward the side or the armature nearest to the ratchet wheel IS. The maximum flux density produced by the solenoid coil 28 extends along the center of the armature opening 22 and this attracts the extended por tion of the bevelled end of the armature toward.

the center of the armature opening; As a result, the upper end of the armature 28 is attracted J against the side 2% of the armature opening 22 1 when the solenoid winding 20 is energized. This substantially assures the armature 28 to assume the position illustrated in Fig. 3 when the .solenoid winding 20 is energized.

If, for some reason or other, the armature 28 is not magnetically attracted to the side 24 of the armature opening nearest to the ratchet wheel 15 upon energization of the solenoid wind ing 20, the bevelled end 35 of the armature forces the armature to engage that side of the armature opening. If the armatureza is not magneth. cally attracted toward theside 24when the arma-L ture is lifted by energization of the solenoid wind- I ihg 20, the bevelled surface 35 engages the upper end 23 of the armature openin 22 to tilt the armature 28 into engagement with the side 24 of the armature opening 22, as is illustrated in Fig. 4. It is here seen that the lower end 29 of the armature 23 also overlies the particular tooth A of the ratchet wheel which is to be engaged' I by the armature upon subsequent dropping thereof.

Accordingly, upon each energization of the solenoid the armature is raised and the lower endof the armature overlies the particular tooth of the ratchet wheel so that when the solenoid I is deenergized, the armature drops by gravity and engages that particular tooth for advancing the ratchet wheel the distance of one tooth. Thus;

foolproof operation is assured. All of this is accomplished without the use of springs and the like which have heretofore conventionally been used. The armature is at all times freely movable and critical control of the armature is eliminated. The'electrically operated mechanism of this invention is also extremely simple in construction' and inexpensive to manufacture and it is capable of operation over long periods of time and underadverse conditions without the necessity of frequent servicing.

Referring now to the form of the invention illustrated in Figs. 5 and 6, the electrically op erated mechanism is generally designated at 40.

The construction of, and manner of operation of, the form of the invention illustrated in Figs.

5 to 8 are very similar to those of the form. of the invention illustrated in Figs. 1 to 4 and like ref-' erence characters have been utilized for like parts. Basically, the electrically operated device 40 differsfrom the electrically operated device II] by the inclusion of a transverse slot 42 in the arma ture 2 8 on the'sideof the armature which is farthest from the ratchet wheel l5. It also differs in constructional details.

The electrically operated device 40 rotatably advances in steps a device generally designated at H, which may include cams I2 mounted on a shaft I3. The ratchet wheel l5, having teeth It, is carried by the shaft I3 and is rotatable about a horizontal axis. The pawl l1, carried by the pin l8, prevents counterclockwise rotation of the ratchet wheel l5. The solenoid, also located above the ratchet wheel l5, includes a suitable electric winding 20 and a laminated core 2| of 'O-shape, forming a magnetic path. The vertically arranged armature opening 22 extends through the bottom of the o-shaped laminated core 2|.

The armature 28, also freely movable in the armature opening 22, has a lower end 29 for engaging the teeth IG of the ratchet wheel l5. It is provided with shoulders 30 for engaging the bifurcations 32 when the armature drops by gravity to limit the downward movement of the armature. The stationary guide means 3| is also provided with a guide surface 33 for guiding the armature in its movement. The upper end of the armature 28 is also bevelled at 35.

The transverse slot 42 in the side of the armature 28 farthest from the ratchet wheel I is in substantial alignment with the bottom of the magnetic core 2| when the armature 281s lifted, as is illustrated in Fig. 6. When the solenoid is energized to lift the armature, the transverse slot 42 lines up with the bottom of the core 2| of the solenoid to make the eifectivespacing between the side of the armature farthest from the ratchet wheel and the core 2| less than the effective spacing :between the side of the armature nearest to the ratchet wheeland the core. As a result, the armature 28 is attracted into engagement with the side 24 of the armature open. ing nearest to the ratchet wheel, as is illustrated in Fig. 6. This lateral attracting of the armature 28 becomes most pronounced just as the armature reaches its upper position upon energization of the solenoid so that the dragging effect of the armatrue 28 along the side 24 of the armature opening is maintained at a minimum and yet the lateral attracting action is entirely effective to position the armature, as illustrated in Fig. 6, when the solenoid is energized. Outside of this difference, the manner of operation of the electrically operated device 40 is the same as the manner of operation of the electrically operated device It and, therefore, a further detailed description is not considered necessary.

The lower end of the armature 28 may be provided with an extension 43 for positively limiting the lateral movement of the lower end of the armature toward the ratchet wheel l5. The solenoid and the ratchet wheel may be suitably carried by a base having a pair of vertically arranged members 45 and transverse members 46 and 41. Angle members 48 are suitably secured to the laminated core 2| and are provided with slots for receiving screws '49 for securing the solenoid to the base. The armature opening 22 in the solenoid may be provided with a suitable nonmagnetic liner 50 and the upper end 23 of the armature opening 22 may be provided with a resilient pad 5| made of synthetic rubber, or the like, to be engaged by the upper bevelled end 35 of the armature 28. This resilient pad 5| effectively operates to prevent burring of the upper end of the armature 28.

' The bifurcations 32 may be integrally formed likewise on the transverse member 41 of the base and the guide means 3| may be secured to the bifurcations 32 by means of screws 52. The pawl I1 is carried between the bifurcations 32 by the pin l8. A pin 53 is preferably provided between the bifurcations 32 to prevent excessive movement of the pawl l1 when the ratchet wheel I5 is removed.

One of the vertical members of the base is provided with a journal 55 which slidably receives a bearing member 56. The bearing member is urged to its inner position by means of a leave spring 51 secured to the base by means of screws 58. The inner end of the bearing member 56 is provided with a hole for receiving the end 59 of the shaft l3 whereby the shaft is journalled for rotation. In order to remove the shaft l3 and, hence, the ratchet wheel l5, all that is necessary is to pull the bearing member 56 against the action of the spring 5'! to release the end 59 of the shaft l3.

While for purposes of illustration several forms of this invention have been disclosed, other forms thereof may become apparent to those skilled in the art upon reference to this disclosure and, therefore, this invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. An electrically operated mechanism for rotatably advancing a device in steps comprising, a toothed ratchet wheel rotatable about a horizontal axis for rotating the device, a solenoid above the ratchet wheel and having a vertical armature opening offset from the horizontal axis of the ratchet wheel, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the teeth of the toothed ratchet wheel, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to engage a ratchet wheel tooth for rotatably advancing the ratchet wheel the distance of one tooth, the side of the armature opening nearest the ratchet wheel being so located with respect to the ratchet wheel that, when the armature is lifted and engages that side of the armature opening, the lower end of the armature overlies the ratchet wheel tooth to be engaged by the dropping armature, and means for moving the armature into engagement with the side of the armature opening nearest the ratchet wheel when the armature is lifted by the solenoid.

2. An electrically operated mechanism for rotatably advancing a device in steps comprising, a toothed ratchet wheel rotatable about a horizontal axis for rotating the device, a solenoid above the ratchet wheel and having a vertical armature opening offset from the horizontal axis of the ratchet wheel, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the teeth of the toothed ratchet wheel, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to engage a ratchet wheel tooth for rotatably advancing the ratchet wheel the distance of one tooth, the side of the armature opening nearest the ratchet Wheel being so located with respect to the ratchet wheel that, when the armature is lifted and engages that side of the armature opening, the lower end of the armature overlies the ratchet Wheel tooth to be engaged by the dropping armature, means for moving the armature into engagement with the side of theiarmature opening nearest the ratchet: wwheel when'the-armature isliited by the solenoid, andi-stopimeans for limiting the dropping movelower-lend with the teeth of the toothed ratchet wheel, said armature-being lifted upon energizationiof the solenoid and dropping by gravity upon-=deenergization of the solenoid to engage a ratchet wheel tooth for rotatably advancing theratchet wheel the distance of one tooth, the

sideiof the armature opening nearest the ratchet wheel being so located with respect to the ratchet wheehthat, when the armature is lifted and engages that side of: the armature opening, the

lower:-end of the armature overlies the ratchetwheel tooth to be engaged. by the dropping armature,- and guide means for the armature for maintaining the spacing between the armature and the side of the armature opening nearest to the ratchet wheel less than the spacing between the armature and the side of the armature opening farthest from the ratchet wheel so that, when the solenoid is energized to lift the armature, the armature is attractedintoengagement with the side of the armature opening nearest to the ratchet wheel;

4. An electrically operated mechanism. for rotatably advancing a device in steps comprising,

a toothed ratohetwheel rotatable about a horizontal ,axisfor rotating the device, a solenoid above the ratchet wheel and having a vertical armature opening offset from the horizontal axis of the ratchet wheel, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the-teeth of the toothed ratchet wheel, said armature being lifted upon energization of thersolenoidand dropping by gravity upon deenergization of thesolenoid to engage a ratchet wheel tooth for rotatably advancing the ratchet wheel the distance of one tooth, the side of the armature opening nearest the ratchet wheel being so locatedwith respect to the ratchet wheel that, when the armature is lifted and engages that side of the armature opening, the lower end of the armature overlies the ratchet wheel toothto be "engaged by the dropping armature, and a bevelled surface on the upper end of the armaturefacing theside of the armature nearest the ratchet wheel cooperating with the upper end of thearmature opening to move the armature into engagement with the side of the armature opening. nearest the ratchet wheel when the armature is lifted by the solenoid.

5. Anelectrically operated mechanism for rotatably advancing a device in steps comprising,

a toothed ratchet wheel rotatable about a horizontal axis for rotating the device, a solenoid above-the ratchet wheel. and having a vertical armature opening offset from the horizontal axis of the ratchet wheel, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the teeth of the toothed ratchet wheel, said armature being lifted upon energizetion;:.of the solenoid and dropping by gravity upon =deenergization v of the solenoid to engage a ratchet wheel tooth for'rotatably advancing the ratchet wheelthe distance of one tooth, the

side of the armature opening nearest-the ratchet" wheel being so located'with respect to the ratchet" wheel that, when the armature is lifted- :andm engages that side of the armature opening,-:the the ratchet :2

lower end of the armaturewoverlies wheel tooth-'to'be engaged by the dropping-arma ture, guide means for the armature for main-3w tainingthe spacing between the armature and theside-of thearmature"opening'nearest to theratchet wheel less thanthe spacing between the armature and the side of the-armature openings farthest from the ratchet wheel so that; whenw the solenoid is energized to lift the armature,- the armature is attractedinto engagemcntwith the side of thearmature opening nearest to the ratchet wheeL-and a bevelled surface 'on the. upper end of the armature facing the sides-oi the armature nearest the-ratchetwheel cooperating with the upper end of thearmature opening l to movethe armature into engagement with the side of the armature opening nearest the ratchet wheel when the armatureis lifted by the solenoid.

6. An electrically:operatedmechanismtor'rotatablyadvancing a device in steps comprising,

a toothed ratchetwheel: rotatable about ahorizontal axis for rotating the device, Y a solenoid above the ratchet :wheel and having an O-shaped: magnetic core-vertically arrangedat rightangles ,1 to the horizontal axis of the ratchet wheel-and w a vertical armature opening extendingthrough the bottom of the magnetic core: and offset from the horizontal "axis of the ratchet'wheel, an

armature of less width than thearmature'openand engageableat its lowerend with the teeth of the toothedratchet wheelysaidsarmaturerbeing lifted upon energization of the solenoidand droppingby gravity upondeenergizationof the sole-' hold to engage a ratchet wheel'tooth for T0?- tatably advancing the ratchetwheel the distance-" of one tooth,-the' side of the armature 'opening tom of the magnetic core when the armature: is

lifted so that, whenthe solenoid is energized' to lift the armature, the armature is attracted-"into engagement with the side of the armature open-' ing'nearestto the ratchet wheel.

'7. An electrically operated mechanism forrotatably advancing'a device-in steps comprising,-

a toothedratchet wheel rotatable about a horizontal axis for rotating the device, a solenoid above the ratchet wheel and having an o sha-ped magnetic core vertically arranged atv right angles to the horizontal axis of the ratchet-wheel-and=- a vertical armature opening extending through the bottom of the magnetic core and-offset from i the horizontal axis of the ratchet wheelpan armature of less width than the armature open-- ingand freely movable in the'armature opening-- and engageable at its lower end with the teeth of the toothed ratchet wheel;said armature-being f lifted uponenergization of the solenoid'and dropping by gravity upon d'eenergizationof the sole noid to engage a ratchet .wheel'x'tooth. :tor rotatably 'advancing thearatchet wheel: the distance:

of one tooth, the smear the armature opening nearest the ratchet wheel being so located with respect to the ratchet wheel that, when the armature is lifted and engages that side of the arma ture opening, the lower end of the armature overlies the ratchet wheel tooth to be engaged by the dropping armature, a transverse slot in the side of the armature farthest from the ratchet wheel and a substantial alignment with the bottom of the magnetic core when the armature is lifted so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the side of the armature opening nearest to the ratchet wheel, and a bevelled surface on the upper end of the armature facing the side of the armature nearest the ratchet wheel cooperating with the upper end of the armature opening to move the armature into engagement with the side of the armature opening nearest the ratchet wheel when the armature is lifted by the solenoid,

8. An electrically operated mechanism comprising, a solenoid having a vertical armature opening, an armature of less width than the armature opening and freely movable in the armature opening, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid, and guide means for the armature for maintaining the spacing between the armature and one side of the armature opening less than the spacing between the armature and the opposite side of the armature opening so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the first mentioned side of the armature opening.

9. An electrically operated mechanism comprising, a solenoid having a vertical armature opening, an armature of less width than the armature openin and freely movable in the armature opening, said armature bein lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid, and a beveled surface on the upper end of the armature facing one side of the armature opening and cooperating with the upper end of the armature opening to move the armature into engagement with that side of the armature opening when the armature is lifted by the solenoid.

10. An electrically operated mechanism comprising, a solenoid having a vertical armature opening, an armature of less width than the armature opening and freely movable in the armature opening, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid, guide means for the armature for maintaining the spacing between the armature and one side of the armature opening less than the spacing between the armature and the opposite side of the armature opening so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the first mentioned side of the armature opening, and a beveled surface on the upper end of the armature facing the first mentioned side of the armature opening and cooperating with the upper end of the armature opening also to move the armature into engagement with the first mentioned side of the armature opening when the armature is lifted by the solenoid.

11. An electrically operated mechanism comprising, a solenoid having a vertically arranged o-shaped magnetic core and a vertical armature opening extending through the bottom of the magnetic core, an armature of less width than the armature opening and freely movable in the armature opening, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid, and a transverse slot in one side of the armature and in substantial alignment with the bottom of the magnetic core when the armature is lifted so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the opposite side of the armature opening.

12. An electrically operated mechanism comprising, a solenoid having a vertically arranged O-shaped magnetic core and a vertical armature opening extending through the bottom of the magnetic core, an armature of less width than the armature opening and freely movable in the armature opening, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid, a transverse slot in one side of the armature and in substantial alignment with the bottom of the magnetic core when the armature is lifted so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the opposite side of the armature opening, and a beveled surface on the upper end of the armature facing said opposite side'of the armature opening and cooperating with the upper end of the armature opening also to move the armature into engagement with said opposite side of the armature opening when the armature is lifted by the solenoid.

13. An electrically operated mechanism for advancing a device in steps comprising, a ratchet member for moving the device, a solenoid above the ratchet member and having a vertical armature opening, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the ratchet member, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to operate the ratchet member, and means for moving the armature into engagement with one side of the armature opening when the armature is lifted by the solenoid for positioning the armature to engage and operate the ratchet member when the armature is subsequently dropped upon deenergiaation of the solenoid.

14. An electrically operated mechanism for advancing a device in steps comprising, a ratchet member for moving the device, a solenoid above the ratchet member and having a vertical armature opening, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the ratchet member, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to operate the ratchet member, and guide means for the armature for maintaining the spacing between the armature and one side of the armature opening less than the spacing between the armature and the opposite side of the armature opening so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the first mentioned side of the armature opening.

15. An electrically operated mechanism for advancing a device in steps comprising, a ratchet member for moving the device, a solenoid above the ratchet member and having a vertical armature opening, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the ratchet member, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to operate the ratchet member, and a beveled surface on the upper end of the armature facing one side of the armature opening and cooperating with the upper end of the armature opening to move the armature into engagement with that side of the armature opening when the armature is lifted by the solenoid.

16. An electrically operated mechanism for advancing a device in steps comprising, a ratchet member for moving the device, a solenoid above the ratchet member and having a vertical armature opening, an armature of less Width than the armature opening and freely movable in the armature opening and engageable at its lower end with the ratchet member, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to operate the ratchet member, guide means for the armature for maintaining the spacing between the armature and one side of the armature opening less than the spacing between the armature and the opposite side of the armature opening so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the first mentioned side of the armature opening, and a beveled surface on the upper end of the armature facing the first mentioned side of the armature opening and cooperating with the upper end of the armature opening also to move the armature into engagement with the first mentioned side of the armature opening when the armature is lifted by the solenoid.

17. An electrically operated mechanism for advancing a device in steps comprising, a ratchet member for moving the device, a solenoid above the ratchet member and having a vertically arranged O-shaped magnetic core and a vertical armature opening extending through the bottom of the magnetic core, an armature of less Width than the armature opening and freely movable in the armature opening and engageable at its lower end with the ratchet member, said armature being lifted upon energization of the solenoidand dropping by gravity upon deenergization of the solenoid to operate the ratchet member, and a transverse slot in one side of the armature and in substantial alignment with the bottom of the magnetic core when the armature is lifted so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the opposite side of the armature opening.

18. An electrically operated mechanism for advancing a device in steps comprising, a ratchet member for moving the device, a solenoid above the ratchet member and having a vertically arranged O-shaped magnetic core and a vertical armature opening extending through the bottom of the magnetic core, an armature of less width than the armature opening and freely movable in the armature opening and engageable at its lower end with the ratchet member, said armature being lifted upon energization of the solenoid and dropping by gravity upon deenergization of the solenoid to operate the ratchet membena transverse slot in one side of the armature and in substantial alignment with the bottom of the magnetic core when the armature is lifted so that, when the solenoid is energized to lift the armature, the armature is attracted into engagement with the opposite side of the armature opening, and a beveled surface on the upper end of the armature facing said opposite side of the armature opening and cooperating with the upper end of the armature opening also to move the armature into engagement with said opposite side of the armature opening when the armature is lifted by the solenoid.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 398,926 Balet Mar. 5, 1889 1,154,266 Murphy Sept. 21, 1915 1,171,021 Canton Feb. 8, 1916 1,855,859 Lesh Apr. 26, 1932 2,192,312 Holslag Mar. 5, 1940 

